Cardinal DiNardo said he wanted to present a "plan of action" to the pope to make reporting of abuse and misconduct by bishops easier.

Referring to the McCarrick case, DiNardo called for a "prompt and thorough examination... into how the grave moral failings of a brother bishop could have been tolerated for so long and proven no impediment to his advancement".

In the US, a group of 5 000 Catholic chief executives have frozen $820 000 in funds paid annually to the Holy See pending clarification of the sex abuse cases.

While Pope Francis has refused to respond to Vigano's allegations so far, the Vatican said on Monday that he was "formulating the eventual and necessary clarifications".

Among the clergymen targeted by Vigano, Cardinal Donald Wuerl, the archbishop of Washington and formerly a bishop in Pennsylvania, is accused of covering up the sexual abuse in that state.

He has said he plans to travel to Rome in the near future to meet with Pope Francis to discuss his resignation.

On Wednesday, the pontiff called for a meeting of all the heads of Catholic bishops' conferences worldwide at the Vatican next February to discuss the issue of the "protection of minors".

More cases are coming to light.

In Germany on Wednesday, the conclusions of a study commissioned by the German Bishops' Conference were leaked to the press.

They included the finding that more than 3 600 children were sexually assaulted by priests in Germany over nearly seven decades.